Surgeons use ultrasonic instruments in surgery to cut and coagulate tissue. Piezoelectric elements are electrically excited at a resonant frequency of an ultrasonic instrument to create vibrations that are transmitted through a resonator and amplified to produce a mechanical, standing wave vibration of the same frequency. An ultrasonic transmission assembly of the instrument has an elongated, transmission waveguide that transmits this vibration to an end effector (e.g., cutting blade) on the distal tip of the instrument. An example of an ultrasonic surgical instrument is the Harmonic Scalpel® Laparosonic® Coagulating Shears, available from Ethicon Endo-Surgery, Inc., Cincinnati, Ohio.
In recent years, minimally invasive robotic systems have been developed and used for certain surgical procedures including coronary artery bypass grafting and cholecystectomy procedures. The robotic systems provide a number of promising benefits that generally reduce the surgical skill required to perform certain surgical procedures, such as by increasing dexterity and eliminating hand tremor. The robotic systems also allow surgeons to perform the procedures at a remote location, wherein remote may be understood as anywhere that is “more than arm's length” from the patient. An example of a robotic surgical system is the DA VINCI, which is available from Intuitive Surgical Inc., Mountain View, Calif.
U.S. Pat. No. 6,783,524 to Anderson et al. titled “Robotic Surgical Tool with Ultrasound Cauterizing and Cutting Instrument” discloses an ultrasonic surgical instrument mounted to a movable arm of a robotic surgical system such as the DA VINCI. The disclosed method for enhancing robotic surgery generally includes coupling the instrument to the robotic surgical system, positioning an end effector of the instrument in contact with tissue at a surgical site and delivering ultrasound energy to the tissue. In general, the disclosed robotic system permits a surgeon to directly control the movements and actuation of the instrument from a remote location.
Despite such advances in surgical technologies, however, considerable skill is still required by surgeons to perform particular steps of some surgical procedures. For example, in order to ultrasonically coagulate a vessel such as the cystic duct of the gall bladder, the surgeon may press a relatively broad surface of the ultrasonic blade against the duct, apply a light clamping force on the duct and sweep the ultrasonic end effector within a treatment region on the duct while applying an intermediate level of ultrasonic power. Then, to cut the duct, the surgeon may present an edge of the blade to the duct, apply a high clamping force on the duct while holding the blade stationary and apply a high level of ultrasonic power. The surgeon may repeat these steps several times during a surgical procedure on a patient.
In order to reduce the time to perform certain surgical procedures and to improve surgical outcomes, surgeons would like to employ various techniques that are not normally practical using current surgical systems. For example, many surgeons would like to have a way to apply a rapidly pulsed clamping force onto tissue while applying ultrasonic energy in order to agitate and/or circulate fluids in the tissue to quicken fluid dessication, thereby shortening the time to coagulate the tissue. Surgeons also would like to have a way to consistently apply the correct power level of ultrasonic energy for the correct duration, primarily in order to avoid injury such as lateral thermal damage to the tissue, but also to quicken the procedure while having the assurance that the tissue seal is hemostatic. Surgeons rely greatly on their physical senses to estimate clamping force on the tissue and the power level/duration of ultrasonic energy that should be applied to the tissue. Obviously, some of this sensory feedback is greatly diminished if the surgeon is using a robotic surgical system and separated from the patient.
Clearly, it may be very difficult, if not impossible, for a surgeon to perform a plurality of surgical tasks in a well-coordinated manner, wherein the tasks may include, for example, sweeping the ultrasonic blade on tissue, rotating the blade, pulsing the clamping force and applying ultrasonic energy at various power levels.
Accordingly, there is a need for an ultrasonic surgical system and method of ultrasonically treating tissue of a patient during a surgical procedure, wherein certain surgical tasks may be automatically and consistently performed, thereby reducing the skill level required by the surgeon to perform the tasks, improving the surgical outcome, reducing the surgical procedure time and further improving the ability to perform surgical procedures remotely.